It is known that the skin has a tendency to become dry as a result of environmental factors (pollution, wind, cold, or conditioned air), psychological factors (fatigue or stress) or hormonal factors (menopause). However, it is important for the skin to be well moisturized and not to suffer water loss, which would run the risk of resulting in withered, dried-out skin. Thus, it is common practice to incorporate into cosmetic compositions substances that rehydrate the skin by taking up atmospheric water and by retaining the water in the skin.
Such an improvement in moisturization may be achieved in many ways, and in particular either using active agents that provide water, such as polyols and especially glycerol, or using active agents that protect the skin's hydrolipid film and thus create a barrier effect, which prevents the loss of water from the skin.
Glycerol is a good moisturizer; however, it has the drawback of giving the compositions comprising it a tacky effect that may be unacceptable if the amount of glycerol is too large. To overcome this drawback, it is known practice to combine glycerol with other moisturizers such as urea derivatives. Urea derivatives that are particularly advantageous are hydroxy urea compounds, which do not have the tacky effect of glycerol.
These active agents are incorporated into conventional supports for topical application compositions. The compositions conventionally used in cosmetics and/or dermatology are especially water-in-oil (W/O) emulsions, oil-in-water (O/W) emulsions and aqueous gels. To stabilize and/or thicken these compositions, it is known practice to add gelling polymers thereto. However, the Applicant has observed that hydroxy urea compounds have the drawback of destabilizing compositions comprising the polymers usually used in cosmetics or dermatology, such as carboxyvinyl polymers of the Carbomer type (CTFA name) or carboxyvinyl polymers comprising a hydrophobic group, such as the products sold under the names Pemulen or Carbopol 1342 (CTFA name: Acrylates/C10-30 alkyl acrylate crosspolymer) by the company Noveon.
There is thus still a need for gelled compositions that are stable in the presence of hydroxy urea compounds, especially cosmetic and/or dermatological compositions.